From A Wiki of Ice and Fire
Andalos is an area of northwestern Essos which was the homeland of the Andals. Due to migration and invasion little is left of the original Andal culture, however.
Andalos is located south of Braavos and the Braavosian Coastland, west of the narrow sea, and east of the Hills of Norvos. Western Andalos near the narrow sea appears to be plains, while further east it becomes hilly and includes the Velvet Hills. The heart of the ancient kingdom of Hugor of the Hill lay in the hills of Andalos. South of the hills were the southern marches of the kingdom, which the Pentoshi now call the Flatlands. A Valyrian road in the Flatlands runs east from Pentos to Ghoyan Drohe and then northeast to Norvos.
The headwaters of the Upper Rhoyne and the Little Rhoyne lie in Andalos.
The hills of Andalos were the homeland of the Andals prior to their invasion of the Fingers in Westeros. Possibly originating from the Axe, the Andals took Andalos from a race of hairy men who were cousins to the Ibbenese. The Faith of the Seven originates in Andalos. It is said that the Seven made themselves manifest in the hills, and thus the Andals felt blessed by the gods. The Father is believed to have pulled seven stars from the heavens to make the crown of King Hugor of the Hill, the first King of the Andals. The Andals eventually migrated to Westeros and conquered most of the kingdoms of the First Men. The True History states the Andals invaded Westeros four thousand years ago, but some maesters claim it was only two thousand years ago.
A Dance with Dragons
Tyrion Lannister and Illyrio Mopatis travel through the Flatlands of southern Andalos after leaving Pentos.
References and Notes